Thats already part of the starter model.
Within your administration module you can find the Account_Overview page, which is the page you are looking for. This module has local account management fully working and available for you. just connect the overview to your navigation and you are good to go.
As Rene said, there are already pages present for the same functionality,
i.e [ Account_Overview ],
But if you want to build it from Scratch,
Then, create a page and add a data grid: set the data source to Xpath and choose Account,
and write the following XPath:
[(System.UserRoles/System.UserRole/System.grantableRoles [reversed()]/System.UserRole/System.UserRoles = '[%CurrentUser%]' or not(System.UserRoles/System.UserRole)) and Name != empty]
Here: we use the expression [reversed ()] to instruct Mendix to read the constraint in the reverse direction to that which it would normally use.
Hope it helps!